1. Field of the Invention
The present invention relates to a reception device, reception method and program, and more particularly to a reception device, reception method and program capable of quickly responding to the occurrence of a flutter.
2. Description of the Related Art
In the event of a flutter which is a significant change in amplitude at short intervals, the reception device must respond to such a change in amplitude by increasing the gain of its AGC (Automatic Gain Control) circuit.
FIG. 1 is a block diagram illustrating a configuration example of a demodulating section provided in an existing reception device.
An AGC circuit 1 adjusts the gain according to the signal from a synchronization circuit 2 to control the amplitude of the receive signal from an unshown antenna. For example, the AGC circuit 1 determines that a flutter has occurred if it does not receive any synchronizing signal from the synchronization circuit 2. As a result, the same circuit 1 increases the gain. The AGC circuit 1 outputs the amplitude-controlled signal to the synchronization circuit 2.
The synchronization circuit 2 performs a synchronization process adapted to establish synchronization with the signal supplied from the AGC circuit 1 and outputs the signal obtained from the synchronization process to the AGC circuit 1 and an equalization circuit 3.
The equalization circuit 3 performs an equalization process on the signal from the synchronization circuit 2 to provide the same phase and amplitude as when the signal was transmitted. Then, the same circuit 3 outputs the equalized signal obtained from the equalization process to the circuit at the subsequent stage.
As described above, existing reception devices perform a type of switching, i.e., increasing the gain of the AGC circuit 1, to handle a flutter if no synchronizing signal is available.
The gain may be increased if a flutter is detected by a flutter detection circuit provided separately rather than if no synchronizing signal is available.
[Patent Document 1] Japanese Patent Laid-Open No. 2000-174829